To add to the list - Gmail.
The tricky thing in Gmail is the little above top left of text box blow the "Add Cc Add BCC Edit Subject Attach a file" bar. If it says "Rich formatting" then you are composing in plain text. If it say "Plain text" you are composing in html format. I'm guessing the intent is that you see what is available to switch to on the toggle. But of course it is confusing to have an indicator that tells you what mode you are not in. Possibly I'm the only person who was ever confused by this, but I doubt it.
Of course you can use pop mail and avoid the Gmail interface. The reason I don't do this for Gmail is that my anti-virus double checks each email as I download, whereas Gmail has no noticeable slowdown for virus checking - so for list management, Gmail is much much faster, in spite of an interface I have mixed reactions to.